PUYALLUP, Wash. — Katie Coats used to work in a crime lab in Seattle. These days, she reports to a quieter research facility about 40 miles south, in the shadow of Mt. Rainier.

Here, Coats wields a surgical blade on her subjects, slicing away small chunks of cells and delicately dropping them in vials to preserve for genetic analysis.

Coats isn't trying to chase down rapists or serial killers. She's using the tissue — which, on a recent day, came from a Canaan fir — to make better Christmas trees.

Or so her boss, plant pathologist Gary Chastagner, hopes.

It's tempting to think the evergreen in your living room is a pristine piece of nature, plucked from a silent and snowy hillside.

In fact, for at least the last 30 years, the majority of American Christmas trees have come from farms, planted in methodically managed rows and tended on a rigorous schedule. They have been bred to have that crisp clean mountain smell and that fresh bluish hue. They've been sheared to get those thick, brushy needles and that tight conical shape.

And a small cadre of researchers such as Chastagner has been perfecting them in the lab too.

These sleuths have spent decades counting and measuring needles and branches, sometimes setting up pop-up labs near Christmas tree lots. Like champion rose growers, they nurture the beauties and weed out the "Charlie Brown trees" that are oddly shaped, or trees that grow too slowly or fall prey to pests.

Armed with a $1.3-million grant from the U.S. Department of Agriculture, Chastagner and his fellow Christmas tree scientists are adding genetic analysis to their arsenal. Their goal is to pinpoint why some trees turn out better than others.

The researchers don't expect consumers to share their interest in tree taxonomies — what makes a spruce different from a pine, or a Douglas fir — not really a "true" fir, they note — different from a balsam, Fraser or noble fir.

"They may know, 'I bought this tree last year, it was a noble fir, I liked the strong branches,'" Chastagner said. "Or they may know, 'I grew up with a Douglas fir and I liked how it smells.'"

His real concern, he added, is that no matter what tree a shopper picks, it does not have any of the annoying inconveniences that make people turn to artificial trees instead of the real thing.

It may not approach the seriousness of halting climate change, but Chastagner sees his quest as a matter of survival for the U.S. Christmas tree industry, which employs about 100,000 people and brings in more than $1 billion a year.

According to the National Christmas Tree Assn., Americans bought 30.8 million farm-grown Christmas trees in 2011, spending an average of $34.87.

Those numbers haven't changed much in the last 50 years, even as the number of U.S. households has grown and tree quality has improved, Chastagner said. In the meantime, sales of "plastic tree-shaped decorations," as a spokesman for the National Christmas Tree Assn. calls them, have been creeping up.

So Christmas tree growers are highly motivated to address the foibles that turn off consumers. (One word: needles.)

Chastagner joined the cause shortly after coming to Washington State University's agricultural research center here in 1978. He spends his autumns visiting tree plantations, big-box stores like Wal-Mart and corner retail lots across the country, hounding salespeople and performing spot inspections of the goods. (His two sons grew up dreading these drive-bys.)

Typically, after peppering a salesperson with questions about deliveries and maintenance, Chastagner gets permission to take a few photos with an ever-present camera and snip away small cuttings from 10 or so trees. Then he will steal away to his car or a table at a nearby fast-food joint, whip out a portable scale, weigh them "fresh" and then send the clippings back to Puyallup to test their moisture content.

Chastagner has analyzed whether using preservatives, fertilizers or chemicals to slow the evaporation of water from leaves will improve needle retention.

By and large, his data suggest, the answer is no.

What usually does work is keeping the trees amply hydrated from the moment they're chopped down to the day they hit the curb for recycling.

As anyone who has visited a Christmas tree lot during Santa Ana winds or struggled to refill water in a too-small tree stand knows, that isn't always so easy. And that's what has led scientists to delve into genetics to try to find the key to breeding trees that won't drop needles.

The first line of genetic research is decidedly low-tech. In Puyallup, 15 acres have been devoted to field trials where Chastagner and his colleagues plant different sorts of firs — noble, Nordmann, balsam, Turkish, even oddball varieties such as Korean or Nikko — to test their mettle. Trees from a single location are grown in a series of plots that vary in key ways: soil moisture, elevation, days exposed to low temperatures and so on.